..Well the two tires are essentially identical in diameter so gearing is the a nonissue. So the main thing would the Moment of Inertia differences between the two sets of wheels. MOI is essentially telling us about the inertia effect when we try to increase or decrease the rotating speed of the wheel and tire. The same amount of mass further from the wheel center increases the MOI so larger wheels and tires actually have to be less massive than stock to have the same MOI. Another way to look at is is that the rolling stock acts like a flywheel. There is a radius squared effect here which is quite powerful. BTW, roughly what are the wheel and tire weights? Thanks.